We live in a noisy world. Some noises can damage our hearing, leading to hearing loss, tinnitus (ringing in the ears), and difficulty communicating especially in background noise. Permanent noise-induced hearing damage is incurable. If you cannot reduce your noise exposure by turning down the volume, moving away from the sound, or limiting the time you are exposed, hearing protection is your only option. But hearing protection comes in so many styles, materials, color, and sizes &#; how can you know which is best for you? National Protect Your Hearing Month is the perfect opportunity to discuss tips for picking the right hearing protector.
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Figure 1: Selection of different hearing protection devices &#; Earplugs, Earmuffs, and Earbands
Obviously, the first consideration in choosing a hearing protector is whether it will block enough noise to reduce your exposure to a safe level. The good news is that most industrial noise exposures are less than 95 dBA, which means most workers require no more than about 10 dB of noise reduction to meet the NIOSH Recommended Exposure Limit of 85 dBA. Almost any hearing protector, when fit correctly, can provide 10 dB of sound reduction. If you do not know the noise levels at your worksite, you can measure them with an app such as the NIOSH Sound Level Meter.
Louder environments demand higher levels of noise reduction, but beware of reducing sound too much. Just as too little light can make it just as difficult to see as too much light, too little sound can make you feel isolated and less aware of their surroundings. Overprotection can be counterproductive, as you may feel the need to remove your hearing protector to hear someone speak or listen to your equipment. Aim for just enough noise reduction to bring your exposure down to 75-85 dBA.
The Noise Reduction Rating on hearing protector packaging represents the amount of noise the hearing protector blocked when tested in a laboratory, but workers usually get much less noise reduction on the job. The best way to know how much noise reduction you are getting from a hearing protector is by fit-testing. If fit-testing is not available at your workplace, you can check earplug fit by counting out loud while slowly cupping and uncupping your hands over your ears; if you have a good fit, your voice should sound about the same as you cup and uncup your ears. NIOSH QuickFitWeb can also be used to check if you are getting more or less than 15 dB of sound reduction.
If you are exposed to noise levels 100 dBA or greater (such as chainsaws or jackhammers) or if you are exposed to impulsive sounds (such as nail gun or weapons noise), you should wear double hearing protection (earmuffs over earplugs).
Workplace characteristics beyond noise levels also need to be considered in choosing the right hearing protector. For example, do you have to wear other head-level personal protective equipment (PPE), such as eye protection, a hard hat, or a respirator? Eye protection (and even some eyeglasses) can interfere with the seal of an earmuff around the ear, allowing sound to leak into the ear. Earmuffs can interfere with the fit of hardhats or helmets; some muffs have a &#;low-profile&#; headband or are designed to be mounted directly onto a hardhat or helmet, eliminating this problem. Make sure that your hearing protection is compatible with other safety equipment you use at work.
Consider also whether the noise at your job is continuous or if it stops and starts at various times during the day. Do you stay in the same place for most of the workday, or move from one area to another? Earmuffs are easier to remove and replace than earplugs, so they may be better for intermittent noise exposures. If earmuffs are not an option due to other issues (e.g., compatibility with other PPE), pre-formed earplugs may be easier to remove and replace than foam plugs. Level-dependent or sound restoration hearing protectors can also be useful for intermittent exposures; these types of hearing protection allow sound to pass through when the background noise levels are low and become protective when noise levels increase.
Do your hands frequently get dirty at work? If so, avoid using foam earplugs which must be rolled down with your fingers before insertion, unless hand-washing facilities are readily available and you have time to wash up each time you need to insert the earplugs. Do you work in a tight space? Earmuffs may not be compatible when working in a confined area. Is it very hot or very cold where you work? Earmuffs can be uncomfortable in hot environments; earmuff cushions can become ineffective in very cold environments.
Finally, think about how frequently you need to hear speech while wearing hearing protection. If spoken communication is common, or if high fidelity sound is important for other reasons (e.g., musicians), flat attenuation hearing protectors may be helpful. Special communication headsets can also improve speech communication in very loud environments.
Once you have narrowed your selection down to hearing protectors that are appropriate for your noise exposure and compatible with your worksite and job tasks, the choice is completely up to you! However, hearing protection only works if you wear it consistently and correctly every time you are exposed to hazardous noise, so choose a protector that is comfortable and convenient.
Many people find earplugs more comfortable than earmuffs, especially when worn for long periods of time or in in hot environments. Earplugs are lightweight, easy to store, and convenient to keep on hand for unexpected exposures. However, earplugs may be harder to learn to fit properly. Some earplugs come in different sizes, so you may need help determining which size is correct for you. If your ear canals are very narrow or very curvy, it may be difficult to find an earplug that will fit. Earplugs are usually inexpensive, but they need to be replaced frequently; some earplugs are designed to be used once only and then discarded.
Earmuffs, on the other hand, are generally one-size devices. Many people find them easier to fit properly and consistently. Earmuffs are easier to remove and replace quickly, so they can be preferable for intermittent use. They are bulkier than earplugs and may be uncomfortable in warm places or tight spaces. They are more expensive, but more durable and last longer than earplugs.
Hearing health relies on knowing how to protect your hearing and how to select the right form of hearing protection. This National Protect Your Hearing Month, take a few minutes to make sure you are using the best hearing protection for your work tasks. Then, wear it every time you are exposed to noise levels above 85 dBA. Your ears will thank you!
CAPT William J. Murphy, Ph.D., is a research physicist with the NIOSH Division of Applied Research and Technology.
Christa L. Themann, MA, CCC-A, is a research audiologist with the NIOSH Division of Applied Research and Technology.
CAPT Chucri (Chuck) A. Kardous, MS, PE, is a research engineer with the NIOSH Division of Applied Research and Technology.
CAPT David C. Byrne, Ph.D., CCC-A, is a research audiologist with the NIOSH Division of Applied Research and Technology.
Additional resources:
NIOSH Personal Protective Equipment (PPE)
Best practice bulletin: Hearing protection-emerging trends: Individual Fit Testing
Hearing protection &#; OSH WIKI
How can I protect my hearing at work?
Back to topThe surest method of preventing noise-induced hearing loss (NIHL) is to eliminate the source or to reduce noise at the source by engineering methods. However, in certain situations, these measures are not possible. In such workplaces, workers may need to wear hearing protectors to reduce the amount of noise reaching the ears.
What are some things I should know about selecting hearing protection devices?
Back to topPeople should wear a hearing protector if the noise or sound level they are exposed to is close to or greater than the occupational exposure limits (OEL) for noise. For most jurisdictions, this occupational exposure limit is 85 decibels (A-weighted) or dBA. Hearing protectors reduce the noise exposure level and the risk of hearing loss when worn correctly.
If hearing protection is required, then a complete hearing conservation program should be implemented. A hearing conservation program includes noise assessment, methods for controlling noise, hearing protector selection, employee training and education, audiometric testing, maintenance, inspection, record keeping, and program evaluation.
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The effectiveness of hearing protection is reduced greatly if the hearing protectors do not fit properly, are not inserted or worn correctly, if they are worn only periodically, or if they are removed even for a short period of time. To maintain their effectiveness, the hearing protection should not be modified. Music earphones or headsets are not substitutes for hearing protectors and should not be worn where hearing protectors are required to protect against exposure to noise.
Select hearing protection that is:
Earplugs are inserted in the ear canal. They may be premolded (preformed), moldable, rolldown foam, push-to-fit, or custom molded. Disposable, reusable and custom earplugs are available.
Semi-insert earplugs consist of two earplugs held over the ends of the ear canal by a rigid headband.
Earmuffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a headband.
The choice of hearing protectors is a very personal one and depends on a number of factors including level of noise, comfort, and the suitability of the hearing protector for both the worker and the environment. Most importantly, the hearing protector should provide the desired noise reduction. It is best, where hearing protectors must be used, to provide a choice of a number of different types and sizes to choose from.
If the noise exposure is intermittent, earmuffs are more desirable since it may be inconvenient to remove and reinsert earplugs.
Manufacturers provide information about the noise-reducing capability of a hearing protector, referred to as an NRR (noise reduction rating) value. The NRR is based on laboratory conditions, therefore, calculations to de-rate the noise reduction rating should be done to reflect workplace conditions (see further below).
CSA Standard Z94.2-14 (R) &#;Hearing protection devices &#; Performance, selection, care, and use&#; defines noise reduction rating as &#;a single number rating that indicates the overall hearing protector attenuation, computed as the difference between the overall C-weighted level of a noise spectrum having equal energy per octave and the A-weighted noise levels under a hearing protector, using mean attenuation data less two standard deviations, derived from the experimenter-fit-procedure of the edition of ANSI Z3.19 (withdrawn) as defined in EPA ()&#;.
The NRR, or other similar systems such as the single number rating (SNR), is a method to more accurately determine the effective exposure of a person when wearing a hearing protector. These rating systems attempt to estimate the actual sound protection provided by hearing protectors when worn in actual working environments (vs. laboratory testing situations). The &#;real world&#; results are often different than laboratory tests with the main reasons for this difference being poor fit, and lack of proper training, supervision, and enforcement. For these reasons, training on the correct fit, and making sure users have a thorough understanding of hearing loss are important elements of the hearing conservation program.
Detailed calculations of the protection provided by a hearing protector involve using octave band analysis of the workplace noise and the noise attenuation provided by the hearing protector for noise in each octave band. Attenuation is defined by CSA Standard Z94.2-14 (R) &#;Hearing protection devices &#; Performance, selection, care, and use&#; as &#;the reduction in sound pressure level incident upon the ear due to the application of a hearing protector or, specifically, the change in hearing threshold level that results when a hearing protector is worn.&#;
Calculating noise attenuation of hearing protection and de-rating noise reduction values (NRR)
Source: CSA Z94.2-14 (R) &#;Hearing protection devices &#; Performance, selection, care, and use&#; Table 2
Earplugs
Percent of NRR achieved: 50%
For use with dBA: Leq &#; [NRR (0.50) &#; 3] = XX dBA
For use with dBC: Lceq &#; NRR (0.5) = XX dBA
Earmuffs
Percent of NRR achieved: 70%
For use with dBA: Leq &#; [NRR (0.7) &#; 3] = XX dBA
For use with dBC: Lceq &#; NRR (0.7) = XX dBA
Dual Protection (use of earplugs and earmuffs)
Percent of NRR achieved: 65%
For use with dBA: Leq&#; [(NRR + 5) (0.65) &#; 3] = XX dBA
For use with dBC: Lceq &#; (NRR + 5) (0.65) = XX dBA
The NRR used for dual-protection calculations is higher of the individual NRRs of the two devices.
Note: Certain CSA Group standards are available for online viewing. To access these, you must first create an account with &#;CSA Communities&#;.
Go to: "https://community.csagroup.org/login.jspa?referer=%252Findex.jspa"
Once you are logged in, click on the text below the &#;OHS Standards / View Access&#; graphic.
Click on the jurisdiction of your choice to see the CSA Standards as referenced in that legislation.
Standards may also be purchased from CSA Group: "https://store.csagroup.org/"
As an example:
Measured workplace noise time-weighted average (TWA) exposure = 98 dBA
Earplug with NRR = 29 dB
Estimated noise exposure = 98 &#; [29(0.5) - 3] = 86.5 dBA
CSA Standard Z94.2-14 (R) provides further guidance on how to apply NRR calculations.
Both types of hearing protection offer advantages and disadvantages.
Earplugs can be mass-produced or individually molded to fit the ear. They can be reusable or disposable. On the positive side, they are simple to use, less expensive than muffs, and often more comfortable to wear when in hot or damp work areas. Some disadvantages are they provide less noise protection than some muffs, and should not be used in areas exceeding 105 dBA. Earplugs are less visible than muffs, making it more difficult to confirm if they are worn. They must be properly inserted and inserted hygienically to provide adequate protection.
Earmuffs can vary with respect to the material and depth of the dome and the force of the headband. The deeper and heavier the dome, the greater the low-frequency attenuation provided by the protector. The headband must fit tightly enough to maintain a proper seal, yet not be too tight for comfort. Some advantages are that earmuffs usually provide greater protection than plugs, although this is not always true. They are easier to fit, generally more durable than plugs, and they have replaceable parts. On the negative side, they are more expensive and often less comfortable than plugs, especially in hot work areas. In areas where noise levels are very high, muffs and plugs can be worn together to give better protection.
The following table summarizes the differences between earplugs and earmuffs.
Comparison of Hearing ProtectionEarplugsEarmuffsAdvantages:
Advantages:
may be worn with minor ear infections
Disadvantages:
Disadvantages:
The human aspects of hearing protection are particularly important since the only useful kind of protection is the protection that is actually worn. Some people do not accept particular kinds of protectors; every human being is different, and the anatomy of the ear and ear canal can vary significantly from person to person.
It is a good idea for the employer to provide a number of different types and sizes of hearing protection from which workers can choose, keeping in mind any safety or hygienic reasons for not providing a particular kind of protector. That is, a particular type of protector should not be used if noise levels are too high or if it proves to be inadequate from a hygienic point of view. For example, earplugs which are used in a plant setting where people reuse them throughout the day, often reinserting them with dirty fingers, can introduce dirt and bacteria into the ears, causing ear infections.
The bottom line on hearing protection is worker preference. If the workers do not like the type of protection (for example, if it is uncomfortable, does not fit well, or is impractical), they will not wear it.
Follow the manufacturer's instructions. With earplugs, for example, the ear should be pulled outward and upward with the opposite hand to enlarge and straighten the ear canal, and insert the plug with clean hands.
In order to get the full benefit, hearing protectors must be worn all the time during noisy work. If hearing protectors are removed only for a short duration, the protection is substantially reduced. The following table gives a maximum protection provided for non-continuous use of an ideally fitted 100% efficient hearing protector. For example, when hearing protection is rated with an attenuation of 25dB, if one takes off their hearing protector for 5 minutes in an hour the maximum protection will be reduced to no more than 11dB.
Impact of removing hearing protectorTime removed (in 1 hr)Maximum 25 dB protection is reduced to (dB)0 minno reduction1 min175 min min830 min360 min0Source: Removal of hearing protectors severely reduces protection. Health and Safety Executive, UK (no date)
Hearing protectors must be used ALL THE TIME to get the full benefit.
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